the way i did it was

but, i know there is another answer of -2 because if you get it is also 1...

so i think that i'm not doing this the proper way

can anyone show me the proper way to solve this?

Printable View

- Apr 25th 2010, 12:37 AMdorkymichellesolving for x with 4th degree polynomial

the way i did it was

but, i know there is another answer of -2 because if you get it is also 1...

so i think that i'm not doing this the proper way

can anyone show me the proper way to solve this? - Apr 25th 2010, 12:41 AMMacstersUndead
Sorry, do you mean, solve ?

EDIT:// I checked your work and there seems nothing wrong with your method. It is quite slick to think of

You could always use polynomial expansion, foiling out if you like, but that wouldn't seem to be worth the effort - Apr 25th 2010, 12:43 AMdorkymichelle
yes sorry!

- Apr 25th 2010, 12:43 AMFailure
- Apr 25th 2010, 12:47 AMMacstersUndead
My mistake; sorry

- Apr 25th 2010, 01:00 AMharish21
- Apr 25th 2010, 01:01 AMTikoloshe
You are dead on with your explanation (that -2 is the other answer). I believe this is the step where the oversight was:

When dealing with an equation involving powers, it is insufficient to take simply the principle root. For an equation of real numbers involving an even power, there are always two roots of positive numbers (the principal root and the negative of the principal root). So implies that or . For odd powers, there is only one root of a positive number. So means the only solution is

If you are dealing with equations over the complex numbers, things are different. By the fundamental theorem of algebra, there roots for a polynomial of degree . So has solutions for . So can picture the solutions as vertices of a polygon in the complex plane (as seen here), with one vertex at the principal root. For even powers you have the symmetry of flipping around the vertical axis which is not present in odd powers. - Apr 25th 2010, 01:24 AMrunning-gag
Double posting is forbidden

http://www.mathhelpforum.com/math-he...-decrease.html - Apr 25th 2010, 01:39 AMdorkymichelle
I'm sorry for double posting

however, on this post, i asked a question that dealt with the algebra part of the problem, it was an algebra concept that I couldn't understand, on the other post, it was a calculus concept.

Should I put it both in one thread next time?